OLIVE  GROWING  IJ   THE  SOUTH.    .  . 
I..ITED  STATES 

^5y~ 

C.   F.   Kinman 
Farmers1   Bulletin  1249 
S.  D.  A. 


FARMERS' BULLETIN  1249 

UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 


_:.  .-    .,   -. 


IN  THE. 

SOUTHWEST 

U  N  IT  ED  STAT  El 


THE  INTRODUCTION  of  olives  into  southern 
California  took  place  150  years  ago,  when  the 
Franciscan  Fathers  made  the  first  plantings  near 
the  San  Diego  Mission.  Since  then  olive  growing 
has  become  widely  disseminated  in  many  parts  of 
California,  in  Arizona,  and  to  a  very  limited  extent 
in  a  few  other  sections,  although  it  is  only  within 
the  past  30  or  35  years  that  the  olive  industry  has 
assumed  a  .place  of  importance  in  the  commercial 
fruit  industry  of  the  United  States. 

The  olive  can  be  grown  successfully  only  in  a  com- 
paratively mild  climate.  A  temperature  of  10°  to 
14°  F.  above  zero  is  likely  to  prove  disastrous  to  the 
tree,  and  the  fruit  will  usually  be  injured  by  a  drop 
below  28°  F.  Furthermore,  there  are  other  limita- 
tions. Although  the  tree  thrives  fairly  well  in  the 
humid  regions  of  the  South,  where  the  temperature 
conditions  are  favorable,  fruit  production  there  is 
not  sufficiently  dependable  to  justify  the  planting  of 
trees.  The  dry  atmospheric  conditions  of  Califor- 
nia and  the  arid  Southwest,  where  the  temperature 
range  is  favorable  and  where  irrigation  supplies  the 
necessary  soil  moisture,  appear  to  meet  the  require- 
ments of  the  olive. 

Though  few  fruit  trees  withstand  the  limited  soil 
moisture  that  the  olive  can  endure,  it  likewise  re- 
sponds, as  do  other  trees,  to  favorable  soil  condi- 
tions; in  fact,  it  is  only  under  such  conditions  that 
regularly  successful  results  can  be  expected. 


Contribution  from  the  Bureau  of  Plant  Industry 
WM.  A.  TAYLOR,  Chief 

Washington,  D.  C.  February,  1922 


36T 


OLIVE    GROWING    IN    THE    SOUTHWESTERN 
UNITED  STATES. 

C.  F.  KINMAN,  Pomologist,  Horticultural  and  Pomological  Investigations. 


CONTENTS. 


Olive  growing  in  the  United  States — 

Cultural  distribution 

Choosing  a  locality  and  site  for   olive 

planting 

Varieties 

Propagation 

Transplanting 

Cultivation  and  irrigation 


Page. 
3 
5 

10 
13 
16 
20 


Fertilization 

Pruning 

Harvesting  the  fruit 

Grading  and  processing  the  fruit 

Insects  and  diseases 

Farmers'  Bulletins  relating  to  fruits 
and  closely  allied  subjects 


Page. 
30 
30 
34 
36 
39 

44 


OLIVE  GROWING  IN  THE  UNITED  STATES. 

NEARLY   a   century   and   a   half  ago  the   Franciscan   Fathers 
brought   to  this  country   some  olives  and  planted  them   at 
the  San  Diego  Mission,  situated  near  the  site  of  the  present 
city  of  San  Diego,  Calif.     This  first  planting,  whether  in  the  form 


FIG.  1. — Trees  of  the  original  planting  of  Mission  olives  at  the  San  Diego  Mission  near 
San  Diego,  Calif.     (Photographed  in  May,  1920.) 

of  cuttings,  seeds,  or  otherwise,  was  the  source  of  what  is  now  known 
as  the  Mission  variety.     From  here,  during  the  next  few  years,  the 

3 


23311O 


Farmers'  Bulletin  1249. 


trees  were  distributed  to  a  number  of  missions  in  southern  and 
central  California.  Some  of  the  original  trees,  also  those  planted 
at  the  other  missions,  are  still  thrifty  and  productive  (figs.  1  and  2). 
The  olive  was  for  many  years  the  most  prominent  fruit  in  Cali- 
fornia; in  fact,  aside  from  the  grape  and  the  fig,  which  were  intro- 
duced by  the  Mission  Fathers  about  the  same  time  as  the  olive  and 
to  each  of  which  has  been  given  the  name  "Mission,"  there  were 

no  other  fruits  of 
importance  in  Cali- 
fornia. On  account 
of  the  sparse  popu- 
lation, only  small 
plantings  of  olives 
were  made,  and  the 
culture  of  these  was 
often  neglected  until 
nearly  a  century 
later,  when  interest 
in  olive  growing  re- 
ceived a  new  impetus 
and  a  few  men 
planted  good-sized 
orchards.  From 
that  time  plantings 
have  continued  to 
increase,  until  to- 
day olive  culture  is 
a  prominent  factor 
in  fruit  production 
in  California  and  is 
of  some  importance 
in  Arizona.  Statis- 
tics show  that  503 
olive  trees  were 
growing  in  Califor- 
nia in  1855 ; J  in 
1876 2  there  were 
5,603  trees  of  bear- 
ing age;  in  1901  the  number  was  539,568;  and  in  1919  3  there  was  a 
total  of  37,412  acres  of  olives  in  California,  with  24,285  acres  in  bear- 

1  Thomas,  Daniel  J.     On  agricultural  statistics  of  the  State.     In  Trans.   Calif.   State 
Agr.   Soc.,  1859,  p.  343.     1860. 

2  Table  of  statistics  .  .  .  1876,  as  reported  to  the  surveyor  general  by  the  several  county 
assessors,  embracing  the  entire  State.     In  Trans.   Calif.    State  Agr.   Soc.,   1876,  p.   125. 
1877. 

8  California  Olive  Association  survey. 


FIG.  2. — A  tree  of  the  original  olive  planting  at  the  San 
Fernando  Mission,  Calif.  The  tree  as  here  shown  was 
cut  back  several  years  ago  to  render  the  harvesting  less 
expensive.  The  present  top  consists  of  sprouts  from  the 
stump.  (Photographed  in  May,  1920.) 


Olive  Growing  in  the  Southwestern  States. 


of   the 

this 


in 


uig.  In  1917  there  were  608  acres  in  olives  in  Arizona.  The  produc- 
tion of  olives  in  California  *  in  1918  was  13,801  tons.  No  accurate 
data  on  the  production  in  Arizona  exists,  but  the  yield  for  1918  has 
been  estimated  at  approximately  100  tons. 

The  importation  of  olives  from  foreign  countries  in  1919  amounted 
to  more  than  3,950,000  gallons ;  also  about  8,300,000  gallons  of  edible 
oil  and  287,000  gallons  for  mechanical  or  manufacturing  purposes. 
Until  1900  almost  the  entire  production  of  olives  in  this  country  was 
utilized  for  oil,  although  for  a  number  of  years  small  quantities  of 
green-olive  pickles  were  made,  and  during  a  few  years  previous  to 
this  considerable  interest  was  given  to  experiments  in  the  processing 

of  ripe-olive  pickles,  the  article 
which   is  now   the  basis 
olive-growing    industry 
country. 

As  there  is  great  interest  in  olive 
planting  and  a  vast  area  of  land 
suitable  for  olive  culture  is  lying 
within  regions  of  congenial  tem- 
peratures in  California  and  Ari- 
zona, there  are  prospects  for  a 
continued  growth  of  this  industry, 
the  profitable  marketing  of  the 
crop  perhaps  being  the  primary 
limiting  factor. 

Natural  conditions  have  never 
given  the  olive  industry  any  seri- 
ous setback,  but  serious  handicap 
has  been  experienced  through  the 
adulteration  of  the  oil  or  the  sale  of  other  oil  as  olive  oil,  when  the 
making  of  the  latter  was  gaining  rapidly  in  importance  during  the  last 
years  of  the  past  century,  and  also  through  the  faulty  sterilization  of 
ripe  pickles,  which  recently  resulted  in  reducing  temporarily  the  con- 
sumption of  this  commodity. 

CULTURAL  DISTRIBUTION. 

The  region  in  which  the  olive  may  be  successfully  grown  for  the 
commercial  production  of  fruit  in  the  United  States  is  not  as  great 
as  for  most  frost-hardy  fruits  and  has  been  confined  to  portions  of 
California  and  Arizona,  although  the  trees  will  live  and  bear  some 
fruit  in  portions  of  all  of  the  southern  tier  of  States  of  this  country. 

*Hecke,  G.  H.  California  crop  distribution  and  estimates,  1918  ...  In  Calif.  State 
Com.  Hort.  Mo.  Bui.,  v.  8,  no.  4,  p.  164.  1919.  In  cooperation  with  U.  S.  Dept.  Agr., 
Bur.  Crop  Estimates. 


FIG.  3. — Outline  map  of  California,  showing 
by  means  of  dots  the  principal  sections 
where  olives  are  grown. 


Farmers'  Bulletin  1249. 


Figures  3  and  4  show  the  regions  in  California  and  Arizona  where 
olive  growing  is  now  a  commercial  industry.  As  with  all  other  fruit 
crops  in  the  comparatively  warm,  dry  regions  of  the  southwestern 
United  States,  the  development  of  the  olive  industry  has  been,  to  a 
large  degree,  centered  in  a  number  of  rather  widely  separated  but 
extensive  sections.  Olives  are  found  scattered  throughout  all  the 
warm  valleys  where  rainfall  or  irrigation  is  sufficient  for  the  needs  of 
the  crop  and  where  the  range  of  temperature  is  favorable. 

The  olive  is  now  grown  commercially  in  at  least  36  of  the  58  coun- 
ties of  California  and  in  a  few  counties  of  Arizona.  The  industry 
extends  from  near  the  border  of  Mexico  to  and  including  Shasta 
County,  which  lies  next  to  the  most  northern  county  of  California. 

This  northern  limit  reaches  nearly 
to  the  forty-first  degree  of  north 
latitude. 

For  convenience,  the  region  of 
commercial  olive  production  is  here 
divided  into  five  natural  sections: 
(1)  The  Sacramento  Valley,  (2)  the 
San  Joaquin  Valley,  (3)  the  central 
California  coast  (the  San  Francisco 
Bay)  section,  (4)  southern  Califor- 
nia, and  (5)  southwestern  Arizona. 

THE  SACRAMENTO  VALLEY. 

The  olive  is  grown  to  a  consider- 
FIG.  4.— outline  map  of  Arizona,  showing  abie  extent  through  the  central  por- 

by   means  of  dots  in   the  general   vi-    . .  „    .,        0  TT   n  i 

cinity  of  Phoenix  the  location  of  the  toon  of  the  hacramento  Valley  and 

principal  olive-growing  section  in  that   the    rolling    foothill    district    to    the 

east  and  north,  with  centers  of  most 

importance  near  Oroville,  in  Butte  County ;  at  Fairoaks,  which  lies 
northeast  of  the  city  of  Sacramento,  in  Sacramento  County ;  and  at 
Corning,  in  Tehema  County.  More  than  14,000  acres  of  olives  are 
growing  in  the  entire  valley,  of  which  over  8,000  acres  are  of  bearing 
age.  Little  attention  is  given  this  crop  in  the  southwestern  portion 
of  the  valley,  which  is  swept  by  cold,  moist  winds  throughout  most  of 
the  summer. 

THE  SAN  JOAQUIN  VALLEY. 

The  San  Joaquin  Valley  joins  the  Sacramento  Valley  and  lies  to 
the  south  of  it.  Although  the  most  extensive  olive  plantings  have 
been  made  in  the  southeastern  portion,  olive  trees  may  be  found  scat- 
tered throughout  the  valley  (fig.  5).  There  are  nearly  11,000  acres 


Olive  Growing  in  the  Southwestern  States. 


'of  olive  orchards  in  this  section,  of  which  5,500  acres  are  in  bearing. 
Nearly  half  of  both  bearing  and  young  trees  are  in  Tulare  County, 
Lindsay  and  Exeter  being  the  principal  centers.  Plantings  in  each 
of  three  counties,  Madera,  Kern,  and  Fresno,  cover  more  than  1,000 
acres,  of  which  little  over  one-half  are  in  bearing.  The  nonbearing 
acreage  (trees  not  of  bearing  age)  in  this  and  in  the  Sacramento 
Valley,  indicates  the  keen  interest  taken  in  this  crop  during  the  past 
few  years.  The  deep,  heavy,  fertile  soils  of  several  types — sandy 
loams  and  gravelly,  dry  adobe — which  characterize  the  southeastern 
portion  of  the  valley  where  olives  are  planted  are  conducive  to  a 
more  vigorous  tree  growth  than  are  the  conditions  in  localities 
farther  north  in  this  valley  or  in  most  places  in  the  Sacramento 
Valley. 

Olive  acreage  in   California  in  1919  l  and  in  Arizona  in  1917,  by  counties. 

CALIFORNIA. 


Section  and  counties. 

Bear- 
ing. 

Non- 
bear- 
ing. 

Total. 

Section  and  counties. 

Bear- 
ing. 

Non 
bear- 
ing. 

Total. 

Sacramento  Valley: 
Butte 

Acres. 
3  229 

A  cres  . 
1.981 

Acres. 
5,210 

Central  California  coast 
(San  Francisco  Bay): 

Acres. 

A  cres  . 

A  cres 

Tehama  

2,006 

1,034 

3,040 

Sonoma  

650 

650 

Sacramento.  . 

1  026 

971 

1,997 

Santa  Clara1  . 

230 

230 

Shasta                  

519 

593 

1,112 

Napa  

202 

202 

Yuba  

586 

533 

1,119 

Other  counties  

212 

15 

227 

Glen  n 

355 

590 

945 

Placer  

343 

70 

413 

Total  

1,294 

15 

1  309 

196 

125 

321 

Sonthprn  Pal'fnrt  'a' 

Total 

8  260 

5  897 

14,  157 

Los  Angeles 

2  717 

330 

3  047 

1  822 

638 

San  Joaquin  Valley: 

San  Diego 

1  521 

245 

1  766 

Tulare. 

2  567 

2,729 

5  269 

San  Bernardino 

901 

502 

1  403 

Madera  

558 

575 

1,133 

Ventura  

1,234 

1  234 

Kern 

111 

721 

1  165 

Santa  Barbara 

492 

63 

555 

Fresno  

629 

469 

1,098 

Orange  

362 

362 

San  Joaquin 

538 

287 

825 

Imperial 

108 

84 

192 

301 

159 

460 

Stanislaus                 .  . 

202 

203 

405 

Total 

9  157 

1  862 

11  019- 

100 

2io 

310 

Mariposa  

235 

235 

Total  for  State.    . 

24,285 

13,  128 

37,  412 

Total  

5,574 

5,353 

10,927 

ARIZONA. 


Counties. 

Acres. 

Counties. 

Acres. 

Yavapai  

12 

Santa  Cruz. 

31 

Maricopa  

499 

Cochise  

5 

Final 

61 

Total  for  State.  .   . 

608 

1  California  Olive  Association  survey.        5  Calif.  State  Com.  Hort.  Mo.  Bui.,  vol.  8,  No.  4,  p.  164. 
THE  CENTRAL  CALIFORNIA  COAST   (SAN  FRANCISCO   BAY)   SECTION. 

Soon  after  olive  culture  had  become  a  factor  in  fruit  growing  in 
California,  that  portion  of  the  State  which  includes  the  counties 
lying  adjacent  to  or  near  San  Francisco  Bay  was  looked  upon  as 


8  Farmers'  Bulletin 

offering  promising  conditions  for  its  culture,  but  owing  to  the  cool, 
moist  sea  breezes  which  prevail  during  the  summer  months  over 
most  of  the  section  the  returns  have  not  warranted  continued  plant- 
ing. Aside  from  the  fruit  not  reaching  a  satisfactory  size,  the 
ravages  of  the  black  scale  are  general  and  severe.  In  some  instances 
olive  trees  in  this  section  have  been  removed  to  make  way  for  the 
planting  of  more  profitable  crops.  In  places  not  swept  by  the  cool 
winds  and  where  climatic  conditions  are  more  like  those  of  the  in- 
terior valleys,  the  olive  gives  satisfactory  returns.  In  1919  a  little 
more  than  1,300  acres  of  olives  were  growing  in  this  locality,  and 
almost  the  entire  area  was  in  bearing. 


FIG.  5. — An  orchard   of  olives  of  the  Mission  variety  in   the  San   Joaquin   Valley,   Calif. 
(Photographed  in  August,   1920.) 

SOUTHERN  CALIFORNIA. 

During  the  early  years  of  the  olive  industry  it  was  in  the  section 
comprising  the  southern  third  of  California,  from  Santa  Barbara 
County  southward,  that  most  of  the  olive  trees  were  planted.  The 
acreage  in  this  fruit  has  continued  to  increase,  although  not  as 
rapidly  during  very  recent  years  as  in  the  interior  valleys  farther 
north.  In  1919  more  than  9,166  acres  were  in  bearing,  which  is  a 
greater  area  than  in  any  of  the  other  sections  mentioned,  and  the 
total  planting  was  11,019  acres,  which  is  about  the  same  as  in  the 
San  Joaquin  Valley  and  considerably  less  than  in  the  Sacramento 
Valley.  The  counties  in  this  section  in  which  olive  culture  has 
reached  greatest  importance  are  Los  Angeles,  Riverside,  Ventura, 
and  San  Bernardino,  although  orchards  are  found  in  all  the  warm 
valleys  where  irrigation  water  is  available.  Plantings  have  recently 


Olive  Growing  in  the  Southwestern  States.  9 

been  made  in  the  Imperial  Valley,  where  considerable  interest  has 
been  aroused  in  this  fruit.  As  in  the  northern  valleys,  plantings  are 
for  the  most  part  confined  to  the  slightly  elevated  places  through 
the  valleys  and  on  approaches  to  and  over  the  low  rolling  foothills 
where  irrigation  water  is  available  and  where  frost  injury  to  the 
fruit  is  least  common. 

ARIZONA. 

Olives  are  grown  commercially  in  a  few  counties  of  Arizona.  The 
only  important  center  of  the  industry  (and,  therefore,  the  only  one 
considered  here)  is  located  near  the  city  of  Phoenix.  In  this  section 


FIG.  tJ. — An  orchard  of  olives  of  the  Mauzanillo  variety  near  Phoenix.  Ariz.     (Photo- 
graphed April  27,  1920.) 

the  scattered  orchards  total  about  500  acres.  Plantings  in  the  re- 
mainder of  the  State  aggregate  about  100  acres.  Most  of  the  or- 
chards in  this  locality  were  planted  near  the  beginning  of  the 
present  century,  although  some  were  set  out  a  number  of  years 
earlier.  The  earlier  plantings  were  for  the  most  part  for  the  purpose 
of  oil  production.  During  the  past  few  years  olive  planting  has 
stopped  almost  entirely,  as  the  interest  in  fruits  has  been  diverted 
to  farm  crops,  of  which  cotton  is  the  most  important. 

Both  tree  growth  and  fruit  production  in  parts  of  this  district 
where  water  for  irrigation  is  available  indicate  that  the  soil  is  fertile 
and  that  natural  conditions  are  satisfactory  for  olive  culture  (fig. 
6).  Climatic  conditions  here  are  similar  to  those  of  the  principal 

67366°— 22 2 


10  Farmers'  Bulletin  12b9. 

olive-growing  districts  of  the  interior  valleys  of  California,  except 
that  the  summers  are  somewhat  hotter  and  the  annual  rainfall  less. 
In  these  sections,  as  in  other  olive-growing  districts,  there  is  dan- 
ger of  injury  to  the  fruit  by  early  freezes  if  the  crop  is  excessive 
and  therefore  late  in  ripening  or  if  the  varieties  planted  are  naturally 
late  in  maturing.  The  Mission  and  Manzanillo  varieties  are  the 
principal  ones  grown  for  pickling,  while  a  few  old  orchards  are 
still  maintained  for  oil  production. 

CHOOSING  A  LOCALITY  AND  SITE  FOR  OLIVE 
PLANTING. 

In  selecting  a  locality  for  establishing  an  olive  orchard,  the  ques- 
tions of  most  importance  to  be  considered  are  for  the  most  part  the 
same  as  for  other  fruits.  They  include  climatic  conditions,  the  mois- 
ture requirements  of  the  trees,  soils,  good  roads,  and  the  distance 
between  the  market  or  processing  plant  and  the  immediate  orchard 
site. 

LOCALITY  FACTORS. 
CLIMATIC   CONDITIONS. 

The  most  satisfactory  climatic  conditions  for  the  olive  are  mild 
winters,  where  killing  frost  does  not  occur  until  late  in  the  fall,  and 
hot  dry  summers.  A  temperature  below  28°  F.  above  zero  will 
usually  injure  the  fruit  and  10°  above  zero  will  prove  detrimental  to 
the  trees.  Cold,  moist,  or  hot  dry  winds  are  not  conducive  to  the 
setting  or  maturing  of  the  fruit.  Cold  dry  winds  are  especially 
damaging  to  the  partially  ripened  fruit,  causing  it  to  shrivel.  Such 
fruit  can  be  used  for  oil  only  and  is  of  second  grade  even  for  this 
purpose.  If  warm  weather  follows  and  there  is  sufficient  moisture  in 
the  soil,  the  fruit  will  usually  regain  its  natural  plumpness.  The 
olive  does  not  blossom  until  after  the  danger  of  spring  frosts  is 
over,  but  it  ripens  its  fruit  very  late  in  the  fall  when  in  most  locali- 
ties in  the  olive-growing  regions  of  California  and  Arizona  there  is 
danger  of  injury  to  the  fruit  by  light  freezes. 

MOISTURE  REQUIREMENTS. 

As  it  thrives  best  in  a  hot  dry  climate  and  the  trees  will  live 
where  protracted  droughts  are  frequent,  it  was  believed  for  some  time 
after  the  olive  was  introduced  into  cultivation  in  the  United  States 
that  irrigation  was  not  necessary  even  where  the  close  planting  of 
the  trees  was  practiced  and  where  no  intensive  dry-farming  systems 
were  employed.  This  belief  resulted  in  unprofitable  returns  from 
many  orchards.  At  the  present  time  it  is  recognized  that,  for  satis- 
factory production,  the  olive  is  as  dependent  as  are  other  fruits 


Olive  Growing  in  the  Southwestern  States.  11 

upon  an  adequate  water  supply.  Owing  to  its  requirements,  of  a 
hot  dry  region  where  the  black  scale  is  not  destructive  and  of  an 
elevated  site  on  rolling  or  sloping  land  for  assurance  against  frost, 
irrigation  is  almost  imperative  for  the  regular  production  of  abun- 
dant crops  of  large  fruit.  Dry  rolling  land  where  irrigation  is  neces- 
sary and  water  for  it  is  available  is  therefore  favorable,  if  not  requi- 
site, to  the  profitable  production  of  olives  for  ripe  pickles.  For 
these  reasons  olives  are  not  being  planted  to  any  extent  for  com- 
mercial orchards  in  localities  where  irrigation  water  is  not  avail- 
able or  where  rains  are  not  sufficient  to  provide  for  a  good  tree 
growth;  for  even  with  a  good  setting  of  fruit  in  such  sections  the 
crop  is  likely  to  prove  unprofitable  because  of  insect  pests  and  be- 
cause of  the  effect  of  other  attending  conditions  which  are  adverse. 
Probably  85  per  cent  of  the  olive  orchards  of  California  and  almost 
the  entire  olive  acreage  of  Arizona  are  under  irrigation. 

SOILS. 

Olives  are  found  growing  on  many  types  of  soil,  but  they  prefer 
those  which  are  well  drained  and  fertile.  Loams,  sandy  or  gravelly 
loams  or  clay  loams,  which  have  not  too  high  a  percentage  of  humus 
or  nitrogen  are  most  satisfactory,  although  adobe  land,  if  watered 
and  given  good  surface  cultivation  to  prevent  the  drying  out  and 
cracking  of  the  surface,  has  given  good  results.  The  belief  that  the 
olive  would  make  a  good  growth  and  produce  profitable  crops  where 
nothing  could  be  expected  of  other  fruits  has  caused  many  failures, 
and  at  present  only  soils  which  are  considered  suitable  for  other  fruit 
crops  are  used. 

Olive  plantings  for  the  most  part  have  been  made  on  reddish, 
brownish,  or  grayish  sandy  or  gravelly  loams  belonging  to  the  resid- 
ual or  old  valley-filling  material  groups,  which  are  friable  and  well 
drained  and  darkened  by  a  desirable  quantity  of  humus.  Although 
these  types  have  proved  to  be  satisfactory,  their  selection  by  olive 
planters  resulted  as  much,  probably,  from  a  choice  of  climatic  condi- 
tions as  of  soil,  as  they  are  the  types  on  the  lower  rolling  foothills, 
where  the  air  drainage  is  good  and  detrimental  frosts  are  not  com- 
mon during  the  ripening  season. 

Profitable  orchards  are  found  also  scattered  through  the  broad 
valley  bottoms  on  fertile,  well-drained,  friable  soil  areas  where  sites 
of  slight  elevation  are  found,  although  the  predominating  soil  type 
of  these  regions  is  characterized  by  a  layer  of  heavy  red-clay  subsoil 
and  of  hardpan  which  prevents  the  penetration  of  tree  roots  and 
water. 

Trees  should  not  be  planted  where  there  is  near  the  surface  a 
stratum  of  hardpan  or  other  material  which  is  impervious  to  water. 


12 


Farmers'  Bulletin  1249. 


In  such  places  the  tree  grows  very  slowly  and  produces  small  crops, 
if  any,  and  sometimes  is  affected  with  die-back  or  exanthema.  Where 
trees  have  been  planted  in  such  soil,  breaking  up  the  subsoil  by  blast- 
ing if  the  stratum  is  beyond  the  reach  of  the  subsoil  plow,  so  that 
water  may  penetrate  it  readily,  is  considered  advisable. 

Where  the  stratum  of  heavy  subsoil  or  hardpan  is  a  few  feet  below 
the  surface  olive  trees  seem  to  do  well  if  good  culture  is  given,  as  they 
are  naturally  shallow  rooted  and  do  not  require  the  depth  of  soil 
demanded  by  some  trees. 


FIG.  7. — An  olive  orchard  near  El  Cajcn,  Calif.     (Photographed  in  1918.) 

Soils  very  rich  in  humus  and  nitrogen  are  inclined  to  result  in 
excessive  wood  growth,  in  only  moderate  crops,  and  in  delayed  ripen- 
ing of  the  fruit.  This  necessitates  considerable  pruning  and  expen- 
sive harvesting  and  involves  occasional  severe  losses  by  the  freezing 
of  the  fruit  before  it  is  ripe  enough  to  harvest.  Olive  trees  will  live 
in  soils  where  the  humus  and  nitrogen  content  is  very  low,  although 
in  such  places  they  usually  make  but  little  growth  and  bear  unprofit- 
able crops. 

SITE  FACTORS. 

Points  of  the  most  importance  in  the  selection  of  an  olive  orchard 
site  are  (1)  air  currents,  (2)  soil  drainage,  (3)  a  contour  suitable 
for  irrigation,  and  (4),  as  with  all  other  commercial  fruits,  areas 
where  cultivation,  harvesting,  and  marketing  may  be  economically 
accomplished.  As  the  fruit  will  be  injured  by  freezing  and  will  not 


Olive  Growing  in  the  Southwestern  States.  13 

ripen  after  it  is  harvested,  the  selection  of  a  site  free  from  low  tem- 
peratures during  the  fall  and  early  winter  is  of  first  importance. 
Low  flat  lands,  the  lower  portions  of  ravines,  and  high  flat  table- 
lands should  therefore  be  avoided ;  sloping  stretches  and  rolling  areas 
with  the  exception  of  the  lower  portions  should  be  chosen,  the  eleva- 
tion above  sea  level  being  of  far  less  importance  than  the  elevation 
above  the  valley  or  depression  immediately  adjoining  (fig.  7).  The 
air  drainage  in  a  depression  of  but  a  few  feet  below  a  frost-free 
area  may  be  so  poor  that  temperatures  sufficiently  low  to  render  fruit 
unsuitable  for  pickling  will  occur.  The  same  is  true  of  the  lower 
portions  of  ravines  through  which  the  heavy  cold  air  flows  to  lower 
levels.  Surface  water  drainage  is  usually  satisfactory  where  the 
slope  is  sufficient  to  insure  air  drainage,  but  care  must  be  taken  to 
avoid  places  where  the  subsoils  are  retentive  of  water.  Places  ex- 
posed to  prevailing  strong  or  dry  winds  should  be  avoided,  on 
account  of  the  danger  of  damage  to  the  blossoms,  the  very  young 
fruit,  or  the  fruit  nearing  maturity.  On  the  other  hand,  moderate 
night  breezes  are  desirable  during  the  ripening  season,  on  account  of 
their  tendency  to  prevent  damaging  frosts. 

VARIETIES. 

The  Mission  variety,  which  is  the  one  generally  accepted  as  the 
best  for  planting  in  sections  of  the  United  States  where  olive  grow- 
ing is  an  industry  and  of  late  years  has  been  most  extensively  planted, 
was  also  the  first  to  be  introduced.  As  it  was  for  many  years  the  only 
variety  available,  it  was  planted  in  most  of  our  present  olive-growing 
regions.  During  the  last  30  or  40  years  of  the  nineteenth  century  80 
or  more  varieties  were  introduced,  mainly  from  Spain,  Italy,  and 
France,  and  grown  in  California.  Most  of  this  work  was  done  in  the 
southern  portion  of  the  State.  Practically  all  of  these  varieties  were 
imported  for  the  purpose  of  manufacturing  oil.  When  the  oil  in- 
dustry was  displaced  by  the  more  profitable  pickling  of  the  large  ripe 
olives,  the  demand  for  most  of  the  small-fruited  sorts  which  had  been 
grown  for  their  oil  disappeared.  As  in  the  importation  of  varieties 
of  other  fruits,  a  large  percentage  of  the  varieties  of  olives  proved 
to  be  unsuitable  for  commercial  planting  in  this  country,  and  most 
of  them  have  been  discarded.  A  few  of  these  varieties,  on  account 
of  ripening  their  fruit  early  in  the  fall  or  owing  to  their  extra  large 
size,  are  still  being  planted  by  those  who  are  partial  to  these  qualities. 
Only  a  few  orchards  of  the  oil-bearing  olives  remain,  the  others  hav- 
ing been  removed  or  grafted  to  large- fruited  varieties. 

The  most  important  varieties  at  present,  aside  from  the  Mission, 
are  the  Manzanillo,  Ascolano,  and  Sevillano.  Plantings  of  a  few 
others)  including  Nevadillo  (Nevadillo  Blanco*),  Redding  (Redding 


14  Farmers'  Bulletin 

Picholine),  Columella,  Rubra,  Uvaria,  Pendulina,  and  Oblonga,  may 
still  be  found,  but  nurserymen  claim  that  there  is  little  demand  for 
trees  of  these  sorts  for  planting.  The  few  really  important  varieties 
have  been  grown  for  a  number  of  years  under  a  wide  range  of  condi- 
tions, and  their  performance  in  a  locality  has  established  their  com- 
parative merits  and  the  advisability  of  their  continued  planting  in 
that  section. 

MISSION. 

The  Mission  variety  was  disseminated  from  the  Mission  plantings 
in  California,  where  it  was  grown  from  importations  from  Mexico 
and  is  now  the  most  important  variety.  It  is  grown  in  all  important 
olive-growing  sections.  Its  popularity  results  from  the  satisfactory 
growth  of  the  tree  and  the  production  and  high  quality  of  its  fruit 
for  both  ripe  pickles  and  oil.  The  fruit  is  medium  to  large  in  size, 
although  varying  considerably  in  this  respect,  depending  upon  the 
size  of  the  crop  and  the  cultural  conditions.  The  fruit  is  usually 
large  if  the  crop  is  light  or  the  cultural  conditions  good  and  is 
smaller  when  the  crop  is  excessive  or  when  unfavorable  growing 
conditions  prevail.  In  shape  it  is  oblique-ovate,  with  a  more  or  less 
decided  point  at  the  apex,  deep  purple  in  color,  turning  to  a  shiny 
jet  black  when  fully  ripe.  The  meat  is  firm  and  separates  from  the 
seed  readily  when  pickled. 

The  Mission  variety  is  superior  for  oil  making,  as  well  as  for 
pickles.  The  tree  is  a  vigorous,  handsome,  upright  grower,  suitable 
for  borders,  avenues,  or  windbreaks,  as  well  as  for  general  orchard 
planting.  The  strong  tendency  of  the  trees  to  make  a  vigorous 
upright  growth  rather  than  to  spread  requires  that  special  atten- 
tion be  given  to  pruning  where  this  variety  is  planted  under  condi- 
tions favorable  for  wood  growth.  It  is  one  of  the  most  resistant 
of  all  varieties  to  the  olive-knot  disease. 

In  some  orchards,  or  with  individual  trees,  much  of  the  fruit 
varies  in  form  from  the  normal  to  a  more  regular  broad-ovate,  with 
but  little  indication  of  the  point  at  the  apex.  These  variations  in 
the  shape  of  fruit  are  peculiar  to  the  Mission  variety.  They  are 
considered  by  many  to  represent  distinct  strains,  while  some  con- 
tend that  these  characteristics  are  the  result  of  local  environment. 
Both  forms  of  olives  may  be  found  on  the  same  tree  and  even  on 
the  same  fruit  stem,  although  the  predominating  shape  of  the  fruit 
on  a  given  tree  is  decidedly  of  one  form  or  the  other.  An  effort  to 
establish  by  bud  selection  or  otherwise  a  strain  of  this  variety  which 
will  regularly  produce  the  better  broad-ovate  type  of  fruit  is  highly 
desirable. 


Olive  Growing  in  the  Southwestern  States.  15 

MANZANILLO. 

The  Manzanillo  variety  was  brought  to  this  country  from  Spain 
and  bears  the  Spanish  name,  meaning  "little  apple,"  probably  so 
because  the  rather  broad  depression  at  the  base  resembles  the  base  of 
an  apple.  The  fruit  is  a  little  larger  than  the  Mission  variety  and 
ripens  somewhat  earlier.  For  this  reason  it  is  a  suitable  sort  for 
planting  in  zones  where  ripe  olives  may  be  harvested  before  the  occur- 
rence of  fall  frosts,  which  would  injure  the  fruit  of  the  later  ripen- 
ing Mission  variety.  The  fruit  is  not  as  firm  as  that  of  the  Mission 
and  therefore  requires  more  careful  handling  when  picking  and 
processing  it.  It  is  also  considered  inferior  to  the  Mission  for  oil 
making.  The  flavor  of  the  ripe  fruit  when  pickled  is,  however,  of 
very  high  quality  and  is  claimed  by  some  to  be  unsurpassed. 
The  fruit  is  of  a  regular  rounded  or  broad-ovate  shape  and  its  color  is 
a  rich  dark  purple,  changing  to  deep  bluish  black  when  fully  ripe. 

The  tree  is  a  vigorous  grower  and  inclined  to  be  broad  and  spread- 
ing, a  shape  which  is  always  desired. 

ASCOLANO. 

The  Ascolano  olive  was  brought  from  Italy.  It  is  one  of  the 
largest  fruited  varieties  grown  in  this  country,  being  a  little  larger 
than  the  Sevillano.  On  account  of  its  large  size  it  has  been  used 
mainly  for  pickling.  The  fruit  is  very  tender  and  requires  special 
care  in  handling.  When  ripe  it  is  a  deep  wine  color  rather  than 
black.  In  shape  it  is  a  broad  oval  except  for  an  inconspicuous  point 
at  the  apex. 

SEVILLANO. 

The  Sevillano  variety  is  grown  to  some  extent  in  a  number  of 
localities  on  account  of  its  large  fruit.  It  is  claimed  to  be  the  large 
olive  imported  from  Spain  and  known  here  as  the  "  Queen."  When 
properly  grown  its  fruit  is  one  of  the  largest  produced  in  this  coun- 
try and  is  said  to  reach  a  greater  size  than  when  grown  in  Spain. 
It  is  of  a  rather  long  oblique-oval  shape,  resembling  the  Mission,  is 
attractive  as  a  green  pickle,  and  makes  a  ripe  pickle  of  fair  quality, 
although  if  allowed  to  get  ripe  on  the  tree  it  is  tender  and  easily 
bruised  and  so  soft  after  processing  that  it  must  be  harvested  when 
only  a  thin  blush  of  red  is  present  in  the  skin.  It  is  usually  pickled 
when  a  yellow  or  straw  color  has  developed  and  before  a  blush  of 
red  appears,  and  sometimes  while  green  in  color,  even  before  signs 
of  maturity  are  present. 

The  Sevillano  is  one  of  the  most  frost-tender  varieties  in  common 
cultivation,  so  far  as  injury  to  the  fruit  is  concerned.  The  tree  is 
vigorous  and  is  considered  a  good  bearer.  Like  the  Ascolano,  its 


16  Farmers'  Bulletin 

greatest  point  of  recommendation  for  commercial  planting  is  the  large 
size  of  the  fruit.  The  demand  for  large  fruit  in  the  eastern  markets 
of  the  United  States  has  resulted  in  stimulating  the  planting  of  the 
Ascolano  and  Sevillano  varieties,  so  that  these  trees  have  of  late 
years  been  very  much  in  demand. 

REDDING. 

The  Eedding  (Redding  Picholine}  variety  was  introduced  from 
France  and  widely  planted  for  the  production  of  oil  under  the  mis- 
taken belief  that  it  was  the  true  Picholine  of  that  country  (California 
Ex.  Sta.  Kpt,  1898-1901,  p.  271).  It  is  still  cultivated  where  the  old 
orchards  have  not  been  grafted  to  other  varieties  or  grubbed  out,  but 
no  new  plantings  are  made  except  to  produce  rootstocks  for  other 
varieties.  The  trees  are  vigorous  growers  and  succeed  under  a  wide 
range  of  conditions.  It  is  an  easy  variety  to  graft.  The  fruit  is 
very  small,  oval  in  shape,  and  of  a  deep  bluish  black  color  when 
ripe.  Though  the  variety  is  exceedingly  prolific,  the  fruit  is  too 
small  for  pickling  and  is  used  entirely  for  oil. 

NEVADILLO. 

The  fruit  of  the  Nevadillo  (Nevadillo  Blanco)  variety  is  a  little 
smaller  than  the  Mission.  Its  shape  is  oval  and  regular  except  that  it 
is  somewhat  blunt  at  both  ends.  When  ripe  it  is  a  deep  shiny  black 
with  a  thin  bloom.  The  ripe  pickles  are  of  good  quality  and  flavor, 
and  the  fresh  fruit  returns  a  high  quality  of  oil.  It  is  too  small  to  be 
considered  first  class  for  pickles.  This  is  one  of  the  first  varieties 
to  be  injured  by  cold,  and  it  is  not  being  planted  to  any  consider- 
able extent  at  present. 

PROPAGATION. 

THE  USE  OF  SEEDS  AND  CUTTINGS. 

The  olive  may  be  propagated  by  seeds  and  cuttings  or  by  budding 
or  grafting.  As  seedlings  do  not  come  true  to  the  variety  and 
therefore  do  not  produce  a  uniform  type  of  fruit,  they  are  grown 
only  for  stocks  on  which  to  bud  or  graft.  By  far  the  greatest  por- 
tion of  the  olive  orchards  in  the  southwestern  United  States  have 
been  grown  from  cuttings,  and  this  method  of  propagation  is  still 
in  use  by  most  orchardists  and  nurserymen.  The  reasons  given  for 
preferring  this  method  are  that  but  little  skill  is  required  in  making 
the  cuttings  and  that  the  trees  are  more  quickly  and  cheaply  grown, 
at  least  to  p.  size  suitable  for  setting  in  the  orchard,  than  budded 
trees.  It  is  claimed  by  some  that  by  budding  or  grafting  a  seedling 
stock,  a  tree  superior  to  one  grown  from  a  cutting  may  be  produced. 


Olive  Growing  in  the  Southwestern  States.  17 

The  great  number  of  orchards  which  have  given  satisfaction  when 

O 

trees  grown  from  cuttings  were  planted  allay  the  doubts  of  most 
planters,  however,  regarding  the  success  of  such  trees. 

For  making  cuttings,  soft  tender  tips  of  branches  or  older  hard- 
wood are  used.  Nurserymen  \vho  require  a  large  quantity  of  olive 
trees  for  their  trade  and  propagate  them  by  cuttings  often  use  the 
branch  tips,  as  it  is  difficult  and  expensive  to  secure  hardwood  cut- 
tings of  suitable  size  in  sufficient  number.  They  are  also  usual>y 
equipped  with  the  necessary  lath  houses  or  other  suitable  means  for 
furnishing  the  shade  and  protection  from  wind  required  by  the  young 
cuttingo  cmv^  lor  keeping  in  proper  condition  the  beds  of  sand  in 
which  the  cuttings  are  placed.  About  4  inches  is  the  usual  length 
for  making  softwood  cuttings.  The  tips  selected  should  be  those  that 
have  completed  their  length  growth  and  are  becoming  firm  but  are 
not  too  hard.  The  condition  of  the  growth,  therefore,  rather  than 
any  particular  period  of  time,  determines  when  the  cuttings  should 
be  made.  When  preparing  a  cutting  for  planting  the  cut  is  made 
just  below  the  node  (the  region  where  a  leaf  occurs),  the  same  as  for 
other  plants.  The  two  lower  leaves  are  then  removed  and  the  others 
cut  back  about  one-half  their  length.  The  cuttings  are  then  placed 
in  the  sand  bed  rather  close  together,  where  they  remain  until  roots 
have  started,  which  under  favorable  conditions  is  but  a  few  weeks. 
They  are  then  transplanted  to  nursery  rows  or  beds,  where  they  are 
left  until  they  are  ready  for  planting  in  the  orchard.  It  is  claimed  by 
some  that  trees  thus  grown  have  a  better  root  system  than  those 
grown  from  large  cuttings. 

For  making  hardwood  cuttings,  branches  three-fourths  of  an  inch 
to  1-J  inches  in  diameter  are  usually  chosen,  although  smaller  or  con- 
siderably larger  ones  may  be  used.  Such  cuttings  are  generally 
made  14  to  16  inches  in  length. 

As  with  most  other  trees,  the  best  time  for  making  hardwood  cut- 
tings is  when  the  wood  is  most  dormant,  which  is  during  January 
and  February.  After  the  cuttings  are  made  they  are  commonly  tied 
in  bundles,  then  placed  in  a  trench,  and  covered  with  moist  soil  or 
other  material  to  encourage  callusing.  When  the  soil  becomes 
warm  in  the  spring,  they  are  placed  a  few  inches  apart  in  the  nursery 
row,  being  planted  10  or  12  inches  deep,  so  that  only  one  or  two 
buds  project  above  the  surface  of  the  ground.  Rooting  takes  place 
readily  under  favorable  conditions.  The  sprouts  which  grow  during 
the  first  season  are  allowed  to  remain  during  that  season.  Then  the 
best  one  for  developing  a  tree  is  selected,  and  all  the  others  are  cut 
off.  Growth  in  the  nursery  row  during  the  second  season  follows. 

67366°— 22 3 


18  Farmers'  Bulletin  1249. 

TOP  GRAFTING. 

Top  grafting  is  possible  on  olive  trees  of  any  age,  and  may  be  done 
at  almost  any  time  of  the  year  with  considerable  success,  although 
the  best  time  to  graft  is  just  as  growth  starts  in  the  spring.  This 
method  of  changing  an  orchard  from  one  variety  to  another  was 
practiced  in  many  cases  in  California  during  the  transition  period 
when  the  demand  for  fruit  suitable  for  pickles  was  superseding  that 
for  the  manufacture  of  oil  and  small-fruited  varieties  were  replaced 
by  large-fruited  ones  (fig.  8). 

Both  grafting  into  the  stumps  of  large  branches  ard  budding  into 
new  shoots,  which  are  allowed  to  grow  for  a  year  or  so  atter  the 


FIG.  8. — An  olive  orchard,  originally  of  the  Nevadillo  variety,  planted  about  1890  near 
San  Fernando,  Calif.  The  trees,  as  they  appear  here,  consist  of  6-year-old  Ascolano 
grafts,  the  original  trees  having  been  top-worked  to  the  latter  variety.  (Photo- 
graphed in  May,  1920.) 

tree  is  cut  back,  are  common  practices  (figs.  9  and  10).  In  prepar- 
ing the  tree  for  grafting,  the  limbs  to  be  replaced  by  the  new 
variety  are  cut  off  at  any  desired  height  by  making  a  smooth,  slightly 
slanting  cut  which  will  heal  over  quickly  and  not  permit  water 
to  stand  on  the  cut  surface.  The  usual  custom  is  to  cut  back  only  a 
portion  of  the  top  at  one  time,  for  fear  of  giving  too  great  a  shock 
to  the  tree,  __  and  the  remaining  branches  are  cut  back  the  following 
year.  If  branches  are  to  be  left  at  the  time  those  to  be  grafted  are 
cut  back,  they  should  be  selected  so  as  to  give  as  much  shade  as  pos- 
sible to  the  remainder  of  the  tree  (fig.  11).  A  coat  of  whitewash 
should  be  applied  immediately  to,  the  trunk  and  stumps  of  branches 
to  be  grafted  as  a  protection  against  sunburn  (fig.  12). 


Olive  Growing  in  the  Southwestern  States. 


19 


The  cutting  back  of  the  branches  is  usually  done  in  late  winter: 
and  the  grafting,  when  the  trees  start  growth  in  the  spring.  As 
large  wounds  on  the  olive  are  inclined  to  heal  over  quickly  and  with- 
out leaving  a  permanent  weak  place  in  the  branch  at  the  point  of 
grafting,  larger  branches  may  be  removed  than  could  be  safely  done 
with  many  kinds  of  fruit  trees.  This  makes  it  possible  to  establish 
the  new  head  low,  which  is  always  desirable  with  the  olive,  as  the 
expense  of  harvest- 
ing the  fruit  is  there- 
by lessened. 

Where  a  large 
branch  is  removed, 
two  or  three  scions 
are  grafted  in,  spaced 
equally  distant 
around  the  stump,  to 
insure  rapid  healing 
over  the  stump  and 
to  furnish  a  more 
satisfactory  number 
of  branches  for  form- 
ing the  new  head 
than  if  one  scion 
were  used.  This  also 
insures  to  some  ex- 
tent against  a  total 
loss  by  the  wind 
breaking  the  young 
branches. 

Both      cleft      and 
bark    grafting     are 
practiced   success- 
fully.    Scions  of 
about  one-fourth  of 
an  inch  in  diameter 
and  bearing  two  to 
four  buds  are  considered  most  satisfactory.    These  should  be  placed 
so  that  the  upper  edge  of  the  beveled  surface  of  the  scion  fits  firmly  to 
the  upper  edge  of  the  stump,  and  the  union  is  tightly  bound  with 
cord  or  tape  and  protected  from  water  with  a  coat  of  grafting  wax. 
Support  should  be  given  the  new  growing  branch  to  prevent  it  from 
being  broken  off  by  the  wind.    This  may  be  done  by  placing  a  long 
stick  beside  the  scion  and  tying  it  firmly  to  the  old  stump  and  the 
new  branch. 


FIG.  9. — One-year-old  olive  scions  in  a  30-year-old  stump. 
(Photographed  May  12,  1920.) 


20 


Farmers'  Bulletin 
TRANSPLANTING 


As  the  olive  is  an  evergreen  tree  and  is  grown  in  sections  where 
only  light  freezes  occur,  transplanting  may  be  successfully  done  at 
almost  any  time  of  year,  although  the  time  accepted  as  the  most 
satisfactory  for  transplanting  this  tree  is  after  the  soil  has  become 


FIG.  10. — Scions  that  have  made  a  growth  of  three  seasons  in  an  old  olive  tree  near  tsa.i 
Fernando,  Calif.      (1'hotographed  in  May,  1920.) 

thoroughly  warmed  in  the  spring,  or  during  the  period  from  about 
March  1  to  May  15.  If  the  earth  is  cold,  the  trees  may  fail  to  start 
growth  for  a  considerable  time,  and  some  of  the  weaker  ones  may 
die.  Only  trees  which  have  been  well  grown  and  have  good  root 
systems  should  be  planted.  Good-si.^ed  holes  should  be  made  in  soil 
that  has  been  thoroughly  prepared  to  a  good  depth  and  the  tree 


Olive  Growing  in  the  Southwestern  States. 


21 


FIG.  11. — Olive  trees  30  years  old  near  San  Fernando,  Calif.,  being  grafted  over  to  an- 
•  other  variety.  The  view  shows  the  trees  during  the  first  season  after  the  grafting 
was  begun.  Another  year,  when  the  scions  have  become  well  established,  the  remaining 
limb  will  be  cut  off  and  grafted.  One  main  limb  is  left  in  order  to  maintain  the  vigor 
of  the  tree  while  the  scions  are  becoming  established.  After  they  are  established  they 
will  maintain  the  tree,  so  that  the  limb  which  now  remains  can  be  safely  cut  off  for 
grafting  the  following  year.  (Photographed  in  May,  1920.) 

67366° — 22 4 


Farmers'  Bulletin 


placed  a  couple  of  inches  deeper  than  it  grew  in  the  nursery.  Well- 
pulverized  moist  earth  should  then  be  filled  in  around  the  roots. 
Olive  roots  dry  out  quickly  when  exposed  to  the  sun  or  wind,  so  it 
is  important  that  they  be  kept  moist  and  covered  until  ready  to  be 
placed  in  the  hole.  As  soon  as  the  trees  are  planted  they  should  be 
well  watered,  and  the  trunks  which  have  been  well  shaded  in  the 
nursery  by  surrounding  trees  will  now  need  artificial  protection  from 
the  sun.  A  heavy  coat  of  whitewash  is  valuable,  but  the  tree  pro- 


FIG.  12. — Recently  grafted  olive  stumps  whitewashed  to  prevent  injury  from  sunburn. 
(Photographed  in  May,  1920.) 

tector  manufactured  for  this  purpose  is  more  satisfactory.  If 
thrifty  trees  are  selected  and  the  work  of  planting  well  done,  the 
growth  should  start  within  a  short  time. 

DISTANCE  TO  PLANT. 

The  distance  for  planting  olive  trees  varies  considerably  in  differ- 
ent localities  and  with  individual  orchardists,  although  the  common 
distance  is  about  25  feet  each  way.  Where  conditions  are  conducive 
to  a  heavy  wood  growth,  30  or  33  feet,  and  in  extreme  cases  even  40 
feet,  has  proved  to  be  not  too  far,  for  where  the  branch  and  leaf 


Olive  Growing  in  the  Southwestern  States. 


23 


growth  is  very  heavy  much  of  the  lower  portion  of  the  tree  is  de- 
prived of  sufficient  light  if  too  close  planting  is  practiced  (fig.  13). 


FIG.  13. — Old  olive  trees  of  the  Mission  variety  which  were  planted  too  close  together. 
As  a  result  the  tops  have  become  very  high,  thus  making  the  harvesting  of  the  fruit 
difficult  and  expensive.  (Photographed  in  May,  1920.) 

Where  olive  trees  are  used  for  windbreaks,  18  to  20  feet  is  a  good 
distance  (fig.  14).  For  borders  or  avenues  (fig.  15),  for  which  pur- 
poses they  are  very  ornamental  and  under  good  culture  are  produc- 


24  Farmers'  Bulletin 

tive,  the  local  conditions  and  the  effect  desired  must  determine  the 
distance  of  planting. 

Where  too  close  planting  has  been  practiced,  growers  have  in  some 
instances  removed  alternate  trees  with  good  effect,  but  planting  an 
orchard  with  this  end  in  mind  is  not  desirable  (fig.  16).  The  olive 
comes  into  profitable  bearing  rather  late,  especially  on  soils  where 
the  tree  makes  a  heavy  wood  growth,  so  when  planted  at  normal 
distances  one  would  secure  only  a  few  harvests  before  the  trees  would 
have  to  be  removed,  and  those  remaining  would  have  been  crowded 
into  an  unsatisfactory  upright  growth. 

The  transplanting  of  large  olive  trees  removed  from  orchards  in 
order  to  increase  the  distance  between  trees  has  resulted  in  an  excel- 


FIG.  14. — A  row  of  unpruncd  olive  trees  near  Exeter,  Calif.,  which  serve  as  a  windbreak 
and  dust  screen.     (Photographed  in  March,  1920.) 

lent  stand  and  a  satisfactory  growth  of  transplanted  trees  (figs.  17 
and  18).  This  result  has  followed  even  where  the  limbs  and  roots 
of  the  removed  trees  have  been  cut  back  to  short  stumps  (fig.  19). 

INTERPLANTING. 

Interplanting  olive  trees  with  deciduous  fruits,  grapes,  and  annual 
crops  is  a  common  practice  while  the  trees  are  young  and  where  the 
soil  is  fertile  and  there  is  an  abundance  of  water  (fig.  20).  Peaches, 
apricots,  and  plums  are  among  the  most  satisfactory  fruit  trees  for 
interplanting,  as  they  come  into  heavy  bearing  early  and  will  with- 
stand heavy  pruning  and  can  therefore  be  retained  for  a  number  of 
years  without  causing  an  unsatisfactory  development  of  the  olive  tree. 
Annual  crops  may  also  be  used,  but  the  planting  of  them  as  well  as 


Olive  Growing  in  the  Southwestern  States.  25 

of  other  fruits  should  be  done  with  caution,  so  as  to  avoid  undue  com- 
petition for  soil  moisture  and  plant  food  between  the  olive  trees  and 
the  interplanted  crop.  Interplantings  should  therefore  be  used  only 
where  moisture  and  plant  food  are  plentiful,  or,  in  case  of  an  annual 
crop,  where  the  planting  is  restricted  to  narrow  strips  between  the 
olive  rows  (fig.  21). 

CULTIVATION  AND  IRRIGATION. 

In  the  warm  dry  regions,  where  most  olive  plantings  have  been 
made,  cultivation  is  very  necessary  for  the  conservation  of  soil  mois- 


FIG.  15. — A  roadside  planting  of  olive  trees  of  the  Mission  variety  near  Phoenix,  Ariz. 
(Photographed  in  April.  1920.) 

ture,  for  maintaining  a  surface  mulch,  and  for  keeping  the  land  free 
from  weeds.  Since  the  soil  in  which  olives  are  grown  is,  for  the 
most  part,  loamy  and  friable,  a  satisfactory  tilth  is  not  difficult  to 
maintain. 

The  system  of  cultivation  generally  followed  in  a  commercial  olive 
orchard  is  to  plow  once  during  the  winter  or  early  spring  and  give 
only  shallow  stirrings  thereafter.  The  plowing  should  be  at  a  mod- 
erate depth  and  finished  a  few  weeks  before  the  blossoms  appear. 
Subsequent  surface  stirrings  should  then  be  given  with  a  cultivator 
or  disk  harrow  in  crdsr  to  maintain  a  soil  mulch  and  destroy  weeds 
which  would  rob  the  trees  of  the  surface  moisture.  In  this  way  the 
subsoil  is  well  protected  against  drying  out  and  the  upper  soil  kept 


26 


Farmers'  Bulletin  1249. 


in  good  mechanical  condition  for  new  feeding  roots,  which  will  grow 
upward  into  it  in  the  early  spring. 

While  a  high  humus  content  is  not  desirable  in  the  olive  orchard, 
a  moderate  supply  is  needed  to  preserve  a  good  physical  condition  of 
the  soil  for  root  growth  and  to  maintain  moisture.  To  secure  this  it 
is  the  common  practice  to  encourage  a  cover  crop  of  wild  vegetation 
during  the  winter  or,  occasionally,  to  sow  in  the  fall  one  of  the 
legumes  commonly  used  for  cover  crops  and  allow  it  to  grow  until 
time  for  plowing  in  the  spring.  It  is  claimed  that  bitter  clover 
(Melilotus  indica)  and  common  vetch  (Vicia  sativa)  have  given  the 


FIG.  16. — An  olive  orchard  near  Fontana,  Calif.,  which  was  originally  planted  too  close. 
This  view  shows  the  orchard  five  years  after  alternate  rows  of  trees  had  been  removed 
to  relieve  the  crowded  condition.  The  tree  development  and  the  production  are  now 
good.  (Photographed  in  May,  1920.) 

best  satisfaction  for  this  purpose.  It  is  important  that  this  crop  be 
not  left  in  the  spring  until  it  has  robbed  the  soil  of  too  much  moisture, 
as  the  period  before  blossoming  is  considered  the  most  critical  so  far 
as  setting  a  good  crop  of  fruit  is  concerned.  On  the  return  of  warm 
days  in  the  spring,  when  evaporation  of  the  soil  moisture  is  consider- 
able, the  combined  effect  of  the  roots  o.f  the  cover  crop  and  of  the 
olive  trees,  the  roots  of  which  are  inclined  to  be  superficial,  dries  the 
surface  soil  quickly.  This  will  result  in  difficulty  in  plowing,  and  the 
plowed  soil  .will  be  left  in  a  rough,  cloddy  condition  if  plowing  is 
delayed. 

The  frequency  with  which  irrigations  are  made  and  the  quantity 
of  water  used  differ,  depending  upon  the  texture  and  depth  of  the  soil 


Olive  Growing  in  the  Southwestern  States. 


27 


and  on  weather  conditions.    In  the  well-drained  sandy  loams,  where 
water  filtration  is  good  and  considerable  water,  as  well  as  plant  food. 


FIG.  17. — A  12-year-old  olive  tree  of  the  Mission  variety  which  was  transplanted  in  1912. 
At  that  time  the  tree  was  cut  back  to  the  height  indicated  by  the  stubs  at  the  level  of 
the  man's  hand.  The  tree  as  here  shown  has  grown  for  eight  seasons  since  it  was 
transplanted. 

may  be  lost  by  seepage,  frequent  light  or  moderate  waterings  are 
preferable  to  infrequent  heavy  ones.    The  vigor  of  the  twig  growth 


28  Farmers'  Bulletin 

of  the  current  season  determines  to  a  large  degree  the  quantity  of 
fruit  which  will  be  produced  the  next  year,  and  a  heavier  and  more 
thrifty  twig  growth  results  where  frequent  waterings  are  given 
rather  than  where  the  soil  is  soaked  and  later  permitted  to  dry  out. 
In  the  moderately  deep  and  fairly  well  drained  soils,  where  by  far 
the  most  olive  orchards  are  found,  every  30  days  is  considered  by 
many  successful  orchardists  to  be  sufficient,  but  by  some  every  three 
weeks  is  thought  not  too  frequent  for  the  economical  watering  of 
bearing  olive  orchards.  Where  water  is  scarce  and  applications  can 
not  be  made  at  regular  intervals  it  Avill  be  best  (where  possible  to  do 
so)  to  irrigate  two  or  three  weeks  before  the  blossoms  appear,  again 


FIG.  18. — Aii  olive  orchard  of  the  Mission  variety  near  Strathmore,  Calif.    The  trees  were 
transplanted  in  1912  and  are  now  20  years  old.     (Photographed  in  March,  1920.) 

when  the  fruit  is  one-third  to  one-half  grown,  and  again  when  it  is 
nearly  full  grown,  or  during  the  first  part  of  September.  At  least, 
the  first  and  last  of  these  irrigations  should  not  be  neglected,  as  they 
are  considered  to  be  most  critical  periods  with  respect  to  both  the 
current  crop  and  the  development  of  the  tree  for  the  following  one. 
When  fall  and  early  winter  rains  are  light,  an  irrigation  should  be 
given  during  this  period,  as  the  olive  is  an  evergreen  and  therefore 
functions  throughout  the  year.  As  evaporation  is  slow  during  the 
winter,  one  early  irrigation  will  usually  be  sufficient  for  an  entire  dry 
winter  if  the  soil  is  in  good  tilth. 

As  with  other  fruits,  care  must  be  taken  that  water  drains  out  of 
the  lower  soil  strata  and  also  from  all  low  areas ;  otherwise  seepage 
water  will  collect  in  such  places  and  cause  serious  injury  to  the  roots. 


Olive  Growing  in  the  Southwestern  States. 


29 


It  is  advisable,  however,  to  leave  implanted  the  depressions  where 
water  and  air  drainage  are  faulty. 

irrigations  that  are  too  frequent  or  too  heavy  often  prove  detri- 
mental where  soils  are  underlain  with  hardpan  or  a  stratum  of  poorly 
drained  material  which  prevents  the  downward  movement  of  water. 


FIG.   19. — An  old  stump  of  a  Mission  olive  tree  near  Oroville,   Calif.,  showing  sprouts 
grown  during  three  years  since  it  was  transplanted.     (Photographed  in  April,  1920.) 

as  olive  roots  are  sensitive  to  excessive  moisture.  Thorough  cultiva- 
tion to  maintain  a  surface  soil  mulch  for  the  purpose  of  conserving 
moisture  and  the  infrequent  and  light  irrigations  should  prove  profit- 
able on  such  land. 

Olives  are,  as  a  rule,  planted  on  friable  soils  where  irrigation  water 
moves  downward  rather  rapidly  and  the  feeding  roots  of  the  trees 


30  Farmers'  Bulletin  12b9. 

\ 

are  inclined  to  be  near  the  surface;  hence,  the  use  of  a  number  of 
irrigation  ditches  between  the  rows,  through  which  the  water  may  be 
passed  and  the  entire  surface  soil  wet  within  a  short  time,  is  generally 
more  satisfactory  than  where  fewer  ditches  necessitate  many  hours 
for  the  percolation  of  the  water  through  the  soil  (fig.  22).  The  use 
of  only  one  or  two  ditches  to  the  row  often  results  in  leaving  broad 
areas  with  insufficient  moisture  between  the  rows,  causing  an  excess 
of  water  to  collect  in  low  places  and  in  subsoils  which  are  naturally 
retentive  of  moisture. 


KIG.  20. — A  live-year-old  olive  orchard  of  the  Manzanillo  variety  interplanted  with  Sul- 
tanina  (Thompson  Seedless)  grapevines  near  Phoenix,  Ariz.  (Photographed  April 
30,  1920.) 

FERTILIZATION. 

Most  soils  on  which  olives  have  been  planted  in  the  region  under 
consideration  are  thought  by  many  to  be  sufficiently  supplied  with 
plant  food  for  satisfactory  olive  production.  Among  olive  growers, 
however,  there  is  a  general  belief  that  fertilizers  are  needed,  and  the 
few  who  have  consistently  applied  them  over  a  term  of  years  claim 
to  have  been  well  repaid  with  increased  crops.  The  elements  most 
needed,  the  quantity  required,  the  time  of  application,  etc.,  are,  how- 
ever, unsettled  questions,  as  systematic  tests  to  determine  the  need  for 
the  elements  commonly  used  in  fertilization  have  never  been  carried 
on  or  even  undertaken  in  olive  orchards  in  this  country.  Such  tests 
would  be  of  great  value  to  the  olive  industry. 

PRUNING. 

The  objects  to  be  kept  in  mind  in  pruning  the  young  trees  are  (1) 
to  establish  the  form  of  tree  which  can  be  most  conveniently  culti- 
vated ;  (2)  to  provide  for  a  broad,  low  bearing  surface  from  which 


Olive  Growing  in  the  Southwestern  States. 


31 


fruit  can  be  economically  harvested;  (3)  to  favor  new  growth  on 
all  parts  of  the  tree  and  admit  light  for  its  development;  (4)  to  re- 
move interfering  or  cross  branches;  and  (5)  to  maintain  shade  for 
the  protection  of  the  large  limbs  against  sunburn.  Although  the 
growing  of  many  varieties  on  a  large  number  of  soil  types  and  over 
a  broad  range  of  climatic  conditions  has  resulted  in  considerable 
divergence  of  opinion  as  to  the  most  profitable  methods  to  follow  in 
pruning,  primers  should  keep  the  above  ideals  before  them  and  let  the 
severity  of  the  pruning  be  determined  by  the  needs  of  the  individual 
tree. 

Before  the  nursery  tree  is  set  in  the  orchard  it  should  be  headed 
back  severely,  leaving  but  3  or  4  inches  of  each  of  the  main  branches. 
It  is  well  also  to  remove  at  this  time  all  branches  which  will  not  be 
required  for  forming  a  desirably  shaped  tree.  For  the  branches 


.KiG.  21. — A  catch  crop  hi  a  young  olive  orchard  of  the  Mission  variety  near  Lindsay, 
Calif.      (Photographed  in  August,   1920.) 

which  are  to  form  the  top  of  the  tree  only  strong  upright  ones  should 
be  selected,  and  these  should  be  spaced  a  few  inches  apart  along  the 
trunk  of  the  tree  and  distributed  at  distances  as  nearly  equal  as  pos- 
sible around  it.  When  the  tree  as  planted  consists  of  a  single  stem 
it  should  be  cut  back  to  the  point  where  one  wishes  the  main  branches 
to  develop,  which  with  most  growers  is  20  to  24  inches  above  the 
ground.  Branching  in  many  orchards  has  been  encouraged  at  but 
a  few  inches  above  the  crown,  but  this  is  not  considered  wise,  as  culti- 
vation is  made  more  difficult  thereby.  Before  planting,  the  roots 
should  also  be  shortened  to  a  length  permitting  them  to  be  placed  in 
the  hole  without  bending  or  twisting,  and  roots  injured  in  digging 
should  be  removed  at  the  point  of  injury.  This  will  be  about  all  the 


32 


Farmers'  Bulletin 


pruning  necessary  if  the  four  or  five  main  limbs  branch  as  desired 
during  the  next  few  seasons,  but  in  places  where  the  upright  growth 
of  these  limbs  is  very  vigorous  and  they  branch  but  little,  they  should 
be  cut  back  during  each  of  the  next  two  or  three  winters  to  the  point 
desired  for  the  next  branching. 

For  the  method  of  pruning  to  be  followed  in  succeeding  seasons 
much  will  depend  upon  local  conditions.  On  light  or  shallow  soils, 
where  wood  growth  is  slow,  little,  if  any,  heading  back  would  bf 
done;  severe  cutting  back  will  usually  result  in  seriously  stunting 
the  growth  of  the  tree.  Pruning  under  these  conditions  should 
consist  for  the  most  part  in  the  removal  of  interfering  branches  and 
in  thinning  out  where  small  branches  are  too  numerous  to  permit  a 


FIG.  22. — A  7-year-old  olive  orchard  of  the  Mission  variety,  near  Phoenix,  Ariz.,  showing 
good  growth ;  also  showing  the  main  irrigation  ditch  and  the  head  ditch,  with  small 
outlets  for  the  water  into  the  orchard  rows.  (Photographed  in  April,  1920.) 

thrifty  development  of  new  growth.  This  method  will  apply  more 
especially  to  varieties  which  are  naturally  inclined  to  be  low  and 
spreading  in  their  habits  of  growth. 

In  very  fertile  soil  where  the  central  or  main  branches  make  an 
excessive  upright  growth  and  are  not  inclined  to  form  strong  satis- 
factorily spaced  lateral  branches,  the  cutting  back  of  these  central 
branches  each  winter  for  a  few  years,  to  induce  the  growth  of  a 
greater  number  of  framework  branches,  is  desirable.  In  a  few  locali- 
ties the  conditions  for  wood  growth  are  so  favorable  that  the  upright 
growth  of  a  few  main  branches,  which  develop  where  little  or  no 
pruning  is  practiced  after  the  first  year,  continues  year  after  year 
at  the  expense  of  the  lower  lateral  branches  until  within  a  few  years 
the  main  portion  of  the  crop  must  be  harvested  from  tall  ladders 


Olive  Growing  in  the  Southwestern  States.  33 

and  at  an  excessive  cost.  Also,  the  shading  of  the  interior  part  of 
the  tree  prevents  growth  there  and  leaves  the  main  body  but  barren 
poles.  The  developing  of  a  broad,  low  fruit-bearing  surface  by 
severely  cutting  back  the  rank  interior  branches  for  two,  three,  or 
four  successive  winters,  to  induce  branching,  has  resulted  success- 
fully, although  the  trees  have  probably  been  delayed  in  coming  into 
bearing. 

Conditions  are  such  that  in  by  far  the  greater  number  of  olive 
orchards  the  growth  of  the  tree  will  come  well  between  these  two 
extremes  of  too  little  and  of  excessive  upright  growth,  and  each 
grower  must  decide  as  to  the  severity  and  regularity  of  pruning 
necessary  to  develop  a  strong,  broad  tree  frame  and  maintain  the 
other  conditions  already  mentioned. 

Where  the  growth  of  the  young  tree  is  so  slow  that  no  pruning 
is  necessary  to  secure  the  open  top  and  spreading  shape,  the  crop 
will  usually  be  too  light  to  be  profitable,  and  orchard  management 
along  lines  of  cultivation,  fertilization,  irrigation,  or  drainage  should 
be  employed  or  adjusted  to  induce  a  more  vigorous  growth. 

In  all  pruning  of  the  bearing  tree  it  must  be  remembered  that 
the  fruit  is  borne  on  the  previous  year's  growth  only,  and  the  crop 
will  be  unsatisfactory  if  this  wood  does  not  make  a  thrifty,  vigorous 
development.  When  no  thinning  out  of  small  twigs  has  been  prac- 
ticed, thick  brushes  of  slender  drooping  growth  with  but  a  very  few 
inches  of  new  wood  often  result.  These  masses  should  be  thinned 
out  to  admit  light  to  the  remaining  wood.  This  is  more  especially 
true  where  the  tree  is  making  poor  or  only  fair  growth.  Where, 
owing  to  exceptionally  favorable  natural  conditions  or  extra  care, 
the  trees  are  very  thrifty  and  vigorous  and  are  making  considerable 
annual  growth,  the  small  branches  do  not  droop  to  a  very  objection- 
able extent,  the  smallest,  weakest  twigs  are  crowded  out,  and  little, 
if  any,  thinning  is  necessary. 

The  olive  tree  is  naturally  very  long  lived  and  reaches  a  large  size, 
and  its  period  of  profitable  production  should  continue  over  many 
years.  Therefore,  the  foundation  branches  should  be  so  developed 
and  the  tree  tops  so  kept  within  bounds  by  regular  thinning  that 
heavy  crops  may  be  borne  and  economically  harvested. 

Of  the  two  principal  varieties,  the  Mission  and  the  Manzanillo, 
the  former  is  much  more  inclined  to  make  a  tall,  slender  growth ;  it 
therefore  requires  considerably  more  attention  at  pruning  time  than 
the  latter. 

Trees  in  many  orchards  where  conditions  for  wood  growth  are 
favorable  have  reached  a  height  where  the  harvesting  of  the  fruit 
is  so  expensive  that  the  orchard  can  not  be  maintained  at  a  satis- 
factory profit,  and  heavy  cutting  back  of  the  tree  tops  has  been  prac- 


34  Farmers'  Bulletin  12W. 

ticed  to  establish  the  bearing  surface  nearer  the  ground.  Such  prun- 
ing should  be  done  with  caution,  as  the  production  of  the  trees  will 
be  held  back  a  few  years  by  this  practice.  When  the  top  branches  are 
severely  and  uniformly  cut  back  a  very  rapid  upright  growth  of  new 
branches  will  follow,  and  usually  at  the  expense  of  fruit  production. 
By  removing  some  of  the  large  branches  and  cutting  others  back  to 
laterals,  but  not  too  severely,  a  more  moderate  growth  of  new  wood 
is  encouraged.  This  also  develops  the  low  branches  by  admitting 
light  and  secures  a  larger  bearing  surface.  The  latter  practice  is 
generally  looked  upon  as  the  more  satisfactory  method  of  the  two. 
The  reheading  of  large,  thrifty  trees  should  in  all  cases  be  followed 
by  the  frequent  thinning  of  some  of  the  vigorous  upright-growing 
branches  which  follow  the  pruning  and  by  the  shortening  of  others, 
to  keep  the  new  head  within  bounds. 

The  open-headed  tree,  often  termed  goblet  or  vase  shaped,  is  the 
form  favored  by  some  growers.  This  form  is  secured  by  cutting  out 
all  central  branches  after  the  main  limbs  have  become  well  estab- 
lished and  allowing  a  heavy  growth  of  lateral  branches  to  develop 
on  the  main  branches,  which  grow  from  the  tree  trunk  at  an  angle, 
but  not  permitting  them  to  fill  the  center  of  the  tree.  While  the 
yield  of  such  trees  will  probably  not  be  as  heavy  under  all  condi- 
tions as  if  some  of  the  central  branches  were  allowed  to  remain,  the 
loss  from  the  injury  caused  by  the  black  scale  will  be  far  less,  owing 
to  the  admission  of  an  abundance  of  noonday  sunshine.  In  sections 
where  this  insect  is  troublesome  this  method  of  pruning  is  often 
practiced  advantageously. 

PROTECTION  OF  LARGE  LIMBS  FROM  THE  SUN. 

Where  large  branches  are  removed  in  pruning  or  cut  back  for  top 
grafting,  thereby  exposing  the  bark  of  the  remaining  large  branches 
to  the  sun,  such  exposed  places  should  be  immediately  covered  with 
a  coat  of  whitewash  to  prevent  sunburn.  The  new  growth  which 
will  appear  all  along  the  branches  within  a  short  time  will  soon  fur- 
nish sufficient  shelter  from  the  sun. 

EXPERIMENTS  IN  PRUNING  NEEDED. 

There  is  an  urgent  need  for  systematic  experimental  work  in  the 
pruning  of  olive  trees.  Such  work  has  not  as  yet  been  carried  on 
in  this  country,  although  there  is  no  subject  connected  with  olive 
production  about  which  the  grower  is  more  keenly  interested. 

HARVESTING  THE  FRUIT. 

As  a  rule,  the  ripening  season  extends  from  two  or  three  to  several 
weeks,  depending  for  the  most  part  upon  the  size  of  the  crop,  but 


Olive  Growing  in  the  Southwestern  States.  35 

also  upon  the  locality  and  the  variety.  Where  the  crop  is  light  it 
may  sometimes  be  harvested  all  at  one  time.  In  the  foothill  sections 
of  the  warm  interior  valleys  of  northern  California  some  fruit  of 
the  early-ripening  varieties  is  sometimes  ready  for  harvest  early  in 
October;  but  in  some  sections  near  the  coast,  where  it  is  cool  and 
often  cloudy  during  the  summer  months,  the  picking  season  is  often 
not  over  until  some  time  in  February.  Three  or  four  pickings  are 
usually  necessary  where  the  crop  is  heavy,  especially  if  the  orchard 
lies  within  the  range  of  the  cool  sea  breezes,  where  ripening  of  the 
fruit  progresses  slowly. 

As  it  is  preferable  from  the  standpoint  of  the  processor  to  gather 
all  the  fruit  at  the  same  stage  of  maturity,  as  there  is  usually  fear 
of  the  fruit  being  injured  by  freezing,  and  also  as  the  orchardist 
wishes  to  keep  his  laborers  employed  after  the  harvest  opens,  har- 
vests are  made  whenever  there  is  sufficient  fruit  to  justify  them. 
Where  a  number  of  pickings  are  necessary,  the  harvest  becomes  very 
expensive,  as  the  fruit  ripens  unevenly  on  all  parts  of  the  tree  and 
the  entire  tree  must  be  gone  over  at  each  picking,  and  except  where 
trees  are  small  much  of  the  fruit  must  be  gathered  from  ladders. 

To  obtain  a  uniformly  good  quality  of  ripe  pickles,  well-matured 
fruit  is  necessary.  The  most  practical  guide  for  the  picker  is  the 
color  of  the  fruit.  Some  canners  of  ripe  olives,  whose  product  is 
looked  upon  by  many  as  the  standard  of  excellence,  insist  upon  hav- 
ing only  deeply  colored  fruit  for  processing.  However,  as  the  fruit 
on  the  lower,  shaded  portions  of  the  tree  does  not  color  as  rapidly  as 
it  does  over  the  outside  branches,  no  color  standard  for  picking  can 
be  strictly  adhered  to,  and  the  picker  must  be  guided  also  by  experi- 
ence. With  modern  methods  of  pickling  olives  the  dark  color  may  be 
developed  even  if  the  fruit  is  immature,  but  immaturity  is  always 
betrayed  by  the  quality  of  the  product,  as  the  meat,  instead  of  sepa- 
rating easily  from  the  pit  and  being  smooth  and  of  a  rich  flavor,  is 
hard  and  brittle,  adheres  to  the  pit,  and  is  lacking  in  richness.  While 
immature  fruit  is  not  satisfactory  for  making  ripe  pickles,  overripe 
fruit  is  also  unsuited  for  this  purpose,  as  it  is  soft  and  becomes 
bruised  during  picking  and  processing. 

Some  large-fruited  varieties  become  very  tender  upon  ripening  and 
must  be  harvested  before  they  are  fully  ripe,  to  avoid  serious  loss  by 
bruising  during  picking  and  processing.  They  are  not  allowed  to 
remain  on  the  tree  after  the  first  blush  of  reddish  color  appears. 

A  maturity  standard  based  on  the  oil  content  has  been  suggested 
as  follows: 

A  minimum  oil  content  of  17  per  cent  in  the  flesh  is  offered  as  a  tentative 
standard  of  maturity  for  Mission  olives  and  other  common  varieties  except  the 
Manzanillo,  Ascolano,  and  Sevillano.  A  minimum  oil  content  of  15  per  cent  is 
recommended  as  a  tentative  standard  for  Manzanillo  olives.  No  standards  for 


36  Farmers'  Bulletin 

maturity  are  recommended  for  the  large-fruited  olives,  Ascolano  and  Sevillano, 
which  must  be  gathered  when  relatively  immature.  These  olives,  however, 
should  not  be  sold  under  the  designation  "  ripe." 

Because  of  the  great  variations  noted  in  the  composition  of  olives  of  the  same 
variety  grown  in  different  localities,  it  probably  will  never  be  practicable  to  set 
definite  and  hard-fixed  minima  for  oil  in  mature  olives,  and  the  proposed  stand- 
ards must  be  applied  with  caution.8 

For  making  ripe  pickles,  careful  handling  of  the  fruit  during 
harvest  has  been  recognized  for  many  years  as  of  first  importance. 
Badly  bruised  or  punctured  fruit  can  not  be  used  for  pickles  and 
must  be  utilized  for  oil.  The  fruit  is  therefore  gathered  by  hand 
and  placed  carefully  in  picking  baskets  or  buckets  and  transferred 
to  lug  boxes  for  hauling  to  the  pickling  plant.  Further  to  insure 
against  bruises,  some  packers  place  some  water  in  the  picking  buck- 
ets to  serve  as  a  cushion  for  the  falling  fruit.  Stripping  fruit  from 
the  branches  with  rakes  and  allowing  it  to  fall  on  canvas  spread 
under  the  tree  is  practiced  occasionally  by  a  few,  but  a  low  per- 
centage of  first-class  products  is  expected  from  such  methods. 

While  somewhat  less  care  is  taken  in  harvesting  fruit  which  is  to 
be  utilized  for  oil  making,  it  is  recognized  that  only  sound,  well-ma- 
tured fruit  will  render  first-quality  oil. 

For  making  green  pickles,  which  is  a  minor  industry  in  this  coun- 
try, large  fruits  only  are  used,  and  these  are  gathered  as  soon  as  they 
are  full  sized  or  when  a  light-yellow  color  indicating  approaching 
maturity  appears,  but  before  the  pink  blush  develops  in  the  skin. 

When  the  processing  plant  may  be  reached  in  a  day  or  so  after 
picking,  the  fruit  is  shipped  in  lug  boxes,  but  when  several  days  are 
required  for  transportation,  barrels  are  used  and  the  fruit  covered 
with  salt  water  to  prevent  bruising  and  spoiling  in  transit. 

GRADING  AND  PROCESSING  THE  FRUIT. 

When  the  fruit  reaches  the  pickling  plant  it  is  first  run  through  a 
sizing  machine  and  separated  into  different  sizes.  During  the  pick- 
ling process  each  size  is  treated  separately,  as  olives  of  uniform  size 
can  be  pickled  more  uniformly  than  fruits  of  different  sizes  handled 
together,  and  the  pickles  are  more  attractive  when  sized.  Fruit  of 
different  varieties  is  kept  separate  throughout  the  pickling  process. 
This  is  necessary,  not  only  for  marketing  but  also  because  the  fruit 
of  different  varieties  is  different  in  texture  and  quality. 

Canners  of  olives  do  not  have  a  uniform  size  standard  into  which 
they  grade  their  fruit,  although  It  appears  that  this  would  be  very 
desirable.  The  difference  in  size  between  grades  with  most  packers 
is  one-eighth  of  an  inch  in  the  narrowest  diameter  of  the  fruit.  All 

6  Hilts,  R.  W.,  and  Hollingshead,  R.  S.  A  chemical  study  of  the  ripening  and  pickling 
of  California  olives.  U.  S.  Dept.  Agr.  Bui.  803,  p.  24,  1920. 


Olive  Growing  in  the  Southwestern  States. 


37 


small  fruit,  which  is  usually  considered  to  be  that  below  nine- 
sixteenths  of  an  inch  in  diameter,  is  utilized  for  oil,  and  the  fruit 
above  that  size  is  graded  into  a  number  of  sizes.  Many  types  of 
machines  devised  for  sizing  olives  are  in  use.  Some  have  screens 
adapted  for  separating  the  fruit  of  different  sizes;  others  have 
rollers  spaced  at  the  desired  distances,  over  which  the  fruit  is  passed, 
while  another  type  has  diverging  rollers,  but  all  adjustable  for 
delivering  the  fruit  sized  according  to  the  required  diameter. 
Handling  the  fruit  in  this  operation  must  be  carefully  done,  and  the 
sizing  machine,  whatever  the  type,  must  be  adjusted  to  prevent 
bruising  the  fruit. 


FIG.    23. — An    olive   pickling  room,    showing    concrete   processing    vats. 

From  the  sizer  the  fruit  is  conveyed  to  vats,  where  the  pickling 
process  starts.  Wooden  or  concrete  vats  of  many  sizes  are  in  use, 
although  in  the  newer  plants  concrete  vats  are  used  almost  exclu- 
sively (fig.  23).  These  vats  are  about  3  feet  wide,  2  feet  deep,  and 
8  to  9  feet  long,  a  convenient  size  in  which  to  give  the  fruit  uniform 
treatment  and  to  handle  it  easily  with  the  least  injury.  Here  the 
bitterness  which  is  in  the  fruit  when  it  comes  from  the  tree  is 
destroyed  by  soaking  in  a  lye  solution,  and  after  the  olives  have  been 
darkened  by  aeration  and  the  lye  removed  by  washing  in  fresh  water 
the  fruit  is  soaked  for  a  few  days  in  salt  water.  It  is  then  removed 
from  the  vats,  graded  as  to  color,  and  canned  with  salt  water  after 
the  bruised  fruit  is  removed.  The  cans  are  now  heated  in  a  water 
bath  or  in  retorts  under  pressure  at  a  temperature  somewhat  above 
that  of  boiling  water. 


23311O 


38 


Farmers'  Bulletin  1249. 


The  California  State  Board  of  Health  has  recently  decided  to 
require  that  all  ripe  olives,  before  being  offered  for  sale  in  that 
State,  be  held  at  a  temperature  of  240°  F.  for  40  minutes  to  avoid 
all  possibility  of  bacterial  contamination. 

Some  variation  of  the  above  method,  which  has  been  in  use  since 
the  pickling  of  ripe  olives  was  first  practiced  in  California,  is  em- 
ployed by  most  olive  canners.  Though  the  details  of  the  method,  as 
outlined,  are  not  carried  out  in  the  same  way  in  all  plants  and  though 
some  claim  secret  variations  or  additions  to  the  customary  treat- 
ment, the  fundamental  principles  of  the  commercial  method  are 
well  known. 


FIG.   24. — Olives  curing  in  salt  in  concrete  vats. 

Ripe  olives  are  cured  also  by  soaking  them  in  strong  brine  or 
mixing  them  with  partially  ground  rock  salt — processes  in  which 
no  lye  is  used  (fig.  24).  In  very  recent  years  a  considerable  quantity 
of  olives  has  been  treated  in  this  way  in  California.  For  these 
processes  only  very  well  ripened  fruit  is  used,  and  from  four  to  six 
weeks  are  usually  required  to  render  the  fruit  palatable.  The  prod- 
uct, which  is  somewhat  shriveled  in  appearance  and  acrid  in  taste, 
is  prized  by  peoples  from  the  Mediterranean  countries.  It  has  not 
been  adopted  to  any  extent  as  a  food  by  Americans. 

Olives  intended  for  green  pickles  must  be  taken  from  the  tree 
earlier  than  those  for  ripe  pickles  and  must  not  be  aerated  during 
the  pickling  process,  as  this  would  result  in  darkening  the  color  of 
the  fruit.  Aside  from  these  variations  and  a  fermentation  process 
to  which  the  fruit  is  subjected  to  develop  the  flavor  characteristic 


Olive  Growing  in  the  Southwestern  States. 


39 


of  green  pickles,  the  method  for  making  the  green  pickles  is  not 
different,  except  in  a  few  respects,  from  that  for  making  ripe  pickles. 
Those  interested  in  the  details  of  olive  pickling  and  oil  making 
may  obtain  inf  orma- 
tion  on  the  subject 
from  Bulletin  No. 
803  of  the  United 
States  Department 
of  Agriculture,  en- 
titled "A  Chemical 
Study  of  the  Ripen- 
ing and  Pickling  of 
California  Olives." 

INSECTS  AND 
DISEASES. 

Insect  pests  and 
diseases  which  cause 
serious  loss  in  com- 
mercial olive  or- 
chards in  the  United 
States  are  few  in 
comparison  with 
those  which  attack 
most  other  cultivated 
fruits.  Among  the 
insects  that  attack 
the  olive  tree  in  this 
country  the  black 
scale  is  the  only  one 
of  importance,  and 
among  the  diseases 
the  olive  knot  is  the  most  destructive,  although  others  of  minor 
importance  are  more  or  less  common. 

INSECTS. 

Saissetia  oleae  Bern.,  or  the  black  scale,  as  it  is  commonly  known 
in  olive-growing  regions  of  the  southwestern  United  States,  causes 
greater  destruction  to  the  olive  in  this  country  than  any  other  insect 
and  is  responsible  for  seriously  curtailing  the  output  of  fruit  in  some 
localities.  It  does  not  confine  its  attacks  to  the  olive,  but  feeds  on 
a  great  number  of  both  deciduous  and  evergreen  plants  which  are 
widely  distributed,  making  it  exceedingly  difficult  to  eradicate,  and 


FIG.    25. — Branches  of  the  Nevadillo  olive  showing  olive 
knots.     (Photographed  in  June,  1920.) 


40 


Farmers'  Bulletin  1249. 


it  must  therefore  be  considered  when  olive  plantings  are  contem- 
plated.   Fortunately,  it  does  not  thrive  in  sections  where  the  sum- 


*  LW&' 


FIG.  26. — A  thrifty  olive  tree  for  comparison  with  the  one  affected  with  die-back  shown 
In  figure  27.     (Photographed  April  3.  1920.) 

mers  are  hot  and  dry,  such  as  is  the  case  in  practically  all  of  the 
olive-growing  sections  which  are  not  cooled  and  moistened  by  sea 
breezes,  and  in  such  places  spraying  is  seldom  necessary  for  its  con- 


Olive  Growing  in  the  Southwestern  States. 


41 


trol.  In  the  damper  regions  along  the  coast,  however,  the  black  scale 
and  the  black  smut  which  accompanies  it  cause  serious  loss  where 
preventive  measures  are  not  used. 


FIG.  27. — A  4-year-old  olive  tree  affected  witn  die-back.     Compare  this  with  the  thrifty 
tree  shown  in  figure  26.     (Photographed  April  3,  1920.) 

DISEASES. 
KNOT   (BACTERIUM   SAVASTANOI). 

The  disease  which  has  caused  the  most  serious  loss  in  olive 
orchards  is  the  olive  knot  (fig.  25),  which  is  produced  by  a  bacterium 
(Bacterium,  savastanoi).  This  bacterium  attacks  all  parts  of  the 
tree,  including  the  leaf  and  fruit  stems,  but  is  most  harmful  on 
small  growing  twigs  and  young  vigorous  trees.  Its  destructiveness 


42 


Farmers'  Bulletin 


is  most  marked  in  localities  where  it  is  warm  and  moist  and  condi- 
tions are  favorable  for  a  rapid  tree  growth.  The  best  preventive 
measure  known  is  cutting  out  the  infected  portions  and  disinfecting 
the  resulting  cuts,  much  as  is  done  in  pear-blight.  As  the  bacteria 
come  from  the  knots  and  are  carried  to  other  parts  of  the  tree  in 
wet  weather  only,  their  spread  may  be  best  prevented  by  pruning 
out  infected  branches  before  the  winter  rains  occur. 

The  variety  most  seriously  damaged  by  this  disease  is  the  Manza- 
nillo,  although  the  knot  is  common  on  a  number  of  the  small- fruited 
varieties  grown  for  their  oil.  It  is  not,  as  a  rule,  a  serious  menace 


FIG.  28. — Olive  twigs  affected  with  die-back  (at  the  left).     The  branch  at  the  right  is  in 

a  normal  healthy  condition. 

to  the  Mission,  Ascolano,  Sevillano,  and  other  large-fruited  varie- 
ties, the  Mission  being  almost  immune  to  it. 

DIE-BACK.  OR  EXANTHEMA." 

The  die-back  of  olive  trees,  which  has  recently  come  into  more  or 
less  prominence  in  a  number  of  localities,  causes  the  dying  back  of 
the  twigs  and  branches.  The  growing  tips  of  leading  branches 
usually  die  first,  and  new  growth  starts  from  nodes  below,  and  these, 
in  turn,  become  stunted  and  die  (figs.  26  to  28).  Affected  trees  fail 
to  bear  fruit,  and  loss  of  a  large  portion  of  the  tree,  if  not  the  entire 


•  Home,  W.  T.     Diseases  of  the  olive.     In  Pac.  Rural  Press,  v.  88,  no.  3,  p.  54. 
Some  diseases  of  the  olive  in  California.    In  Olive  Jour.,  v.  1,  no.  9,  p.  4,  1917. 


1914. 


Olive  Growing  in  the  Southwestern  States.  43 

tree,  follows  within  a  few  years.  The  trouble  is  most  common 
where  subsoil  drainage  is  faulty.  Blasting,  subsoiling,  or  other- 
wise opening  the  subsoil  to  permit  a  free  circulation  of  moisture 
and  air  through  it  is  thought  to  be  the  most  practicable  remedy. 

DRY-ROT.7 

Attacks  of  dry-rot  result  in  the  shriveling  and  browning  of  spots 
in  the  flesh  of  the  fruit,  and  in  some  seasons  it  causes  considerable 
trouble.  The  diseased  spots  take  lye  during  the  pickling  process 
more  readily  than  the  surrounding  healthy  tissue,  and  great  care  must 
be  taken  during  processing  if  the  affected  fruit  is  to  be  used  for  ripe 
pickles. 

Olive  growers  should  be  constantly  on  the  lookout  for  destructive 
insect  pests  and  diseases  which  cause  preventable  loss  either  to  the 
tree  or  fruit.  Both  insect  and  disease  problems  should  be  referred 
without  delay  to  either  a  State  agricultural  experiment  station  or  to 
the  United  States  Department  of  Agriculture  for  advice.  The  timely 
use  of  preventive  or  control  measures  may  prevent  serious  loss. 

7  The  Olive  Journal,  vol.  1,  No.  5,  October,  1916,  p.  7. 


WASHINGTON  :  GOVERNMENT  FEINTING  OFFICE  :  1922 


UNIVERSITY  OF  CALIFORNIA  AT  LOS  ANGELES 
THE  UNIVERSITY  LIBRARY 

This  book  is  DUE  on  the  last  date  stamped  below 


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